The objective of the proposed research is to gain a better understanding of the role the gut peptide, peptide YY (PYY), plays in the regulation of enteric and extraenteric physiology. The specific aims of the research proposal are: 1. To characterize the mechanisms (i.e., neural or endocrine) involved in oral meal-stimulated release of peptide YY (PYY). 2. To characterize the mechanisms involved in the stimulation of adrenal epinephrine and cortisol secretion by PYY. 3. To study the mechanism by which PYY can modulate neurally-stimulated release of pancreatic insulin and gastric acid secretion. 4. To investigate the effect of PYY neutralization on the secretory responses of the stomach and of the exocrine pancreas. It is hoped that the above research will contribute to our understanding of the role of PYY in normal gut physiology as well as in pathologicaAl circumstances.